Forum: Ruby on Rails Advice: Managing errors w/"too big for session" objects

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Bb4bdf2b184027bc38d4fb529770cde5?d=identicon&s=25 Wes Gamble (weyus)
on 2006-12-28 18:32

I ran into a situation where I was receiving "marshal data too short"
errors on my Apache/FCGI combination (yes, I know about Mongrel, etc.)
when I was displaying errors using the standard scaffolding error
scheme.  I solved this problem but wanted some advice/feedback on my

Here is the original code from my controller that I was using to handle
the errors:

  flash[:current_job] = @current_job
  return redirect_to( :action => 'job_params' )

The problem with this was that @current_job is a huge object with a big
object graph and this was blowing up my session (since flash is a
session object) when I would do the redirect back to 'job_params'.

My solution is below.  I created a clone of the @current_job object and
then populated that new object's errors array (since AR::Base.clone does
only a shallow copy).  Then, of course, my view executes
error_messages_for() on what's in flash[:job].

I have a couple of questions:

1) Is the loop on errors.each_full the best way to handle getting the
errors onto the new object?  I couldn't see a way to just copy the
errors from @current_job to flash[:job] wholesale.

2) Is there a better way to handle this?  I don't think so given that
the errors array has to be handled somehow.

3) Does it make sense, in general, to "render" your errors but redirect
on success?  In this particular case, I really do have to redirect even
on the errors because the destination page is performing an AJAX call
triggered by an "onload" event.  But oftentimes, I could see one just
rendering in the error case since the instance variables are already
available for the destination view.

  flash[:job] = @current_job.clone
  @current_job.errors.each_full do |err|
  return redirect_to( :action => 'job_params' )

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